514 FRANK D. ADAMS 



in two or more sets crossing one another. These lamellae are very 

 narrow, often taxing the power of the microscope to resolve them, 

 but there is scarcely a calcite individual in the slide which is not 

 crowded with them. It is thus evident that every individual grain 

 in the rock has been affected by the movement and has changed its 

 shape to a greater or less extent. When, however, the marble has 

 been very highly deformed, movement is also seen to have taken place 

 by granulation of the rock. In any single section the granulation has 

 a tendency to develop along two intersecting planes, but as the 

 deformation becomes more pronounced, the two series tend to 

 converge and follow a more nearly horizontal course, and a single 

 little line of granulation can often be seen to follow a minutely zigzag 

 line running alternately in the direction of one series and then of the 

 other, the resultant course of the line being transverse to the column 

 and at right angles to the pressure. In this way the deformed column 

 tends to break transversely with a slightly uneven surface, as men- 

 tioned above. It is to be noted that the marble does not show any 

 tendency to develop a cleavage except in a direction at right angles to 

 the pressure. 



h) Deformation with fusible metal as an embedding material. — A 

 column of the marble was then deformed, using fusible metal as an 

 embedding material. The column and tube were of the same 

 dimensions as in the experiments just described and the load required 

 for maximum deformation was 35,000 lbs. The surface of the 

 marble after deformation was found to be lusterless and displayed 

 none of the intersecting lines seen when the rock is deformed in 

 paraffine. The deformed column resembled in shape certain of the 

 columns deformed in paraffine, but the rock itself was converted into 

 a uniform chalky looking material which was much more friable than 

 the marble deformed in parafi&ne. The mass was soaked in balsam, 

 and thin sections were prepared from it. These, when examined 

 under the microscope, were found to present essentially the same 

 characters as in the case of the marble deformed in paraffine and just 

 described. The twinning, however, was less marked and the granu- 

 lation more pronounced. 



c) Deformation with sulphur as an embedding material. — A col- 

 umn of marble of the same dimensions as before was then deformed 



